When to use gravity load?

I always hane this confusion as when to use the gravity load in anlysis. As I understand its nothing but self weight of component being analysed. If this is the case why is that this is not used in all analysis. What should be done if analysis is done on assemblies. Please correct me if i am wrong.

The effect of gravity is usually negligible unless your part/assembly has high mass. The question to ask is: will the part/assembly mass impose significant stress/deformation? If not, ignore it. You can easily do a test with and without gravity load and see if it makes a difference to the results.

The effect of gravity is usually negligible unless your part/assembly has high mass. The question to ask is: will the part/assembly mass impose significant stress/deformation? If not, ignore it. You can easily do a test with and without gravity load and see if it makes a difference to the results.

You should pretty much always use gravity as a load. One case that might not need it is if you were to design a machine that would be constructed out of parts that were already in a zero-g state, and the machine would always be in a zero g state. So unless you work for the International space station, gravity is a good idea. The benefit of including it is that if the effects are not negligible, you don't need to re-run your study. Also, adding gravity to a study does not add any extra time to the solver stage or the mesher stage.

We had a guy at our work here who ran a study for 8 hours (overnight). In the morning, he declared, "well, it looks like everything is working, so I'll just turn on gravity and run it again!" What a waste of time.